Heating unit and heating system for kilns



March 1927' M. L. MUELLER )iEATI NG UNIT AND HEATING- SYIISTEM FOR KILNS3 Sheets-Shoot 1 wl-mental: muuq mgu lmlum iiifi "Filed Oct- 11, 1926amid-i. WA gma m 1 621,333 March 15, 1927. L. MUELLER v HEATING UNIT ANDHEATING SYSTEM FOR KILNS 1nunn ifii fuuuw -(.l] HUM umun 1/ 4 H R VMarch 15, 1927. M. L. MUELLER 6 1,333

HEATING UNIT AND HEATING SYSTEM FOR KILNS Filed Oct. 11, 1926 3 Shee .3-

' will be enhanced.

Pa tented Mar. 15,

UNITED STATES PATENT OFFICE.

MORITZ L. MUELLER, OF SEATTLE, WASHINGTON, ASSIGNOR TO NORTHWEST BLOWERKILN COMPANY, OF SEATTLE, WASHINGTON, A CORPORATION OF WASHINGTON.

HEATING UNIT AND HEATING SYSTEM FOR KILNS.

Application filed. October 1 1, 1926. Serial No. 140,902.

This invention relates to kilns and, to a heating unit and a heatingsystem for the same and it has for its object to provide a novel heatingapparatus, and to bring about a new combination and corelation of parts,whereby marked economies in manufacture will be effected and'theefliciency of the kiln omies and improvements in operation will be morespecifically pointed out'in the following detailed description.

In the accompanying drawings- Fig. 1 is a fragmentary horizontalsectional View of a kiln arranged for thereception of fiat piled lumber.

Fig. 2 is a partial longitudinal sectional view through the kiln of Fig.1.

Fig. 3 is a partial horizontal sectional View of a kiln arranged for thereception of edge piled lumber.

Fig. 4 is a transverse, vertical sectional View, on line 44; of Fig. 1.

Fig. 5 is a transverse, vertical sectional view on line 5-5 of Fig. 1.

Fig. 6 is a plan view of a bank of heating pipes made up of a pluralityof the units, one of which is illustrated in Fig. 5.

Fig. 7 is a fragmentary View illustrating two of the units andillustrating the staggered relation of adjacent units and Fig. 8 is aface vicw of the combined supports and partitions by which the heatingpipes are carried.

Like numerals designate corresponding parts in all of the figures of thedrawing.

In the drawing, 5 designates the body of the kiln. A motor 6 drivesthrough belt 7, to companion blowers 8 and 9. These blowers serve tomaintain a circulation of air in the direction indicated by the arrows.In the forms illustrated in the Figs. 1 and 2, the air is dischargedfrom the blowers into a central conduit 10, and upwardly through-ports11. to and through stacks of fiat piled lumber (not shown) in themanner, indicated in Fig. 3 of Patent #1.4-37.385,

' issued to me .on November 28. 1922-. The air passes outwardly throughchannels formed in the stacks of lumber 'toward the sides it communicatewith the suction sides of:

the blowers. Thus, a circulation in the direction of the arrows ismaintained, as pre- The nature of these econ- Vious'ly stated. In thearrangement illustrated in- Fig. 3, the same disposition of the blowersis maintained but the circulation is reversed with respect to Figs/1 and2;

."that is, in this case, the motor 6 drives through a belt 7 to blowers8? and 9. In this case, the central channel, 15, is the sac: tionchannel and the side channels 16 and 17, constitute the pressureconduits. That is, these are the channels which are con-- nected to thedischarge sides of the blowers.

Thus, the flow 'in this case passes from the channels 16 and 17 upwardlythrough ports 18 at the sides of the kiln and downwardly through stacksof edge piled lumber, (not heated and it is in the provision of a novelheating means and in the novel disposition of this means with relationto the conduits of the kiln, that this invention particularly resides.

Prior to my invention the means most generally employed for heating airin kilns of this character comprised banks of vertical steam pipes,'madeup of a large number of pipe units of inverted U-shape, connected attheir lower ends by cast iron headers. These banks of steam pipes wereusually disposed either in the longitudinal air con duits of the kiln orelse wholly outside of the kiln and in juxtapositiiin to the blowercasings. longitudinally extending runs of steam pipes disposed in theair'conduits.

In contradistinct'ion to these former arrangements, the presentinvention contemplates the. employment of heating means comprising aplurality of cross-horizontal. return bend. steam coils, disposed insuch relation to both the pressure and suction conduits as to projectinto the path of the air flowing through both of said conduits. That is,each individual coil is thus projected into the path of both theoutgoing and the returning air so that the one heating unit heats theair both before it enters the blower casings and after it leaves theblower casings. I

The banks of steam pipes referred to are made up of a plurality of unitsconsisting Other types of kilns employed of a number of convolutions ofreturn bend pipes, one of said units being indicated at in Fig. 5. Thepipes of a unit are passed through channel shaped bars 21. See Figs.

1, 6 and 8. In placing a plurality of these units together to make acomplete bank of heating pipes as illustrated in Flg. 6, these channelshaped bars are butted together, so

.that complementally, they constitute a platethe suction conduits andthe pressure conduits of the air circulatory system. It will be observedthat the pipes of the several units are of such length as to projectinto all of these conduits so that the same heating element is traversedby the air both on its way to the blowers and on 1ts way. from theblowers.

By referring to Figs. 7 and 8,'1t will be observed that the severalunits are alterstandard an nately vertically staggered with respect toeach other. Each unit is connected at its upper end with a steam supplyprpe 23, and at its lower endby suitable branch plpes 24, with a commondischarge or return pipe 25. The latter may be connected by a suitablebranch 26 with a steam trap or other suitable point of discharge.

Among the' advantages of a heating unit of the type herein shown anddescribed, ar-

ticularly when used in relation to the iln herein illustrated, are thefollowing:

Since 'the sections are separate from each.

other anysection may be removed for repair, the number of sections maybe reduced or increased at will, and, in case of leakage, one sectionmay be 1 plugged out until it is convenient to repair it, withoutaffecting the operation of the kiln. A heater of this character is muchless expensive to construct than the types previously used in likerelation, owing to the omission of the cast iron headers or bases .ofother types. Furthermore every fart forming the heater is a universallyused product of pipe and steel manufacture. Such use of standardmaterials permits of more economical manufacture and repair than wherespecial parts have to be renewed. Further-.

more the use of a lurality of individual coil sectionsmakes t e severalunits considerably lighter and capable of more ready disconnection andremoval for repairs than the relativel heavy parts heretofore employedfor t is purpose. The close fitting, upright supporting'channel ironpartitions, previously ascribed, eliminate the necessity of employing aspecial plate for this purbe apparent from an inspection of the drawingthat the partitions are not located in the same position when fiat piledlumber is being treated as when edge piled lumber is being treated andif it be desired .to make a change of the method of loading during, thelife of the kiln, the adaptabilityof these partitions above referred to,constitutes a feature of marked economy in the operation of such kilns.In addition the disposition of the radiation or heater in such a waythat it extends the" full width of the kiln and occupies space in boththe pressure and suction ducts, reduces to a minimum the space in thekiln building used for heater purposes. Further, the aforesaid locationof the radiation and the adaptability to varying positions of themovable partitions, makes it possible to vary the heating effect, theair resistance and the capacity of either the suction, air or thepressure air conduit, by spreading or. by drawing together the saidpartitions and further, permits a complete balance of heating efi'ect,air resistance and distribution of heat at any time. Since the airpasses through the heating elements in opposite directionsthecondensation in all of the coils is automatically balanced,

since each coil, through its position, emanates the same B. t. u. heatconductance over the total surface. The fact that.the steam, thecondensation water and the air from the steam all travel naturallydownward through the steam coils, prevents air binding and sluggishwater movement and makes it the ideal radiation for dry kil'ns where theradiation is inaccessible and under the control of inexperienced steamengineers. This type of radiation is particularly adapted for use withhigh velocity air passing through the pipes, which produces more rapidcondensation, high steam velocity and greater air volume in the steam,which results in less air binding. This cross-horizontal radiation is ofparticular utility in kilns of. the type herein shown and describedemploying forced circulation. The provis on. of radiation of individualsections, va-

riable as to number and each of which may I be varied as to the numberof pipes it contains, permits an adjustmentof air resistance, freeareas, temperature range and heating surface, in relation to the airflow, far greater than is possible with any radiation hitherto appliedto drying kilns. The

arrangement of the radiation where tion air ducts,

in the kiln in respect to the position of pipes, steam supply andcondensation return, is novel, par ticularly by reason of the steam flownever opposing vious types of kiln radlatlon. Thus, a great increase inradiation power is obtained, which shortens materially the time requiredto perform a given drying operation with a given amount of steam and.radiation. Attention is particularly directed to the fact that the pipesupports are solid or one piecemembers instead of being divided in twohalves consisting of several members. Hitherto one sheet constructionhas been unavailable in the return bend type of radiation due to thespace requirements for screwing down the return bends' In my type ofradiation this. is accomplished by placing the channel sup1 center ofthe pipe lengt while assembling the section. When the assembly of thepipe and return bends is complete the two sup-' out to their finalposition are moved they act not only as supports but as partitions ashereinbefore described. Furthermore the use of channel shaped pipesupports not only renders it possible to employ the solid one piecemembers but affords a ready means of fastening one section to anotherwith bolts or other fastening devices which pass through the abuttingflanges of therespective bars.

It is'to be understood that the invention is not limited to the preciseconstruction set forth but that it includes within its purview whateverchanges fairly come within'either the terms or the spirit oi theappended claims. 1

Havingdescribed my invention what I ports 1. In combinationwith a kilncomprising elongated pressure air and suction air ducts and means formaintaining a flow of air therein, of a, transversely extending heatingunit of such lenth as to lie within and substantially span such pressureair and Suesouice. p 2. The combination with a'forced circu lation kilncomprising pressure air and suction air ducts, of ,blower means formaintaining a circulation of air throu h said duct, a heatingl unit ofsuch lengt as to extend across t substantially span the suction airducts where both going to and means for supplying a such unit from anexternal source.

3. In combination with a forced circulation -kiln comprising a floor,the space heneath which is divided into three conduits in one of whichthe air flows in one'direcy the air is heated the flow of condensate asin preorts back, in theand means for supplying aheating fluid to suchunit from an external e kiln in such position as to, ressure air and theand leaving the blower means,v heating fluid totion and in the other twoof which the air flows in the opposite direction, there being portsleading from the several ducts throughthe floor of the kiln, of aheating means disposed within the kiln and comprising a pluralityof'transversely extending steam pipes of such length as to overlap andlie partly within allof said ducts and blower means outside of the pointof location of the heating means adapted to maintain a circulationthrough said ducts,

the air is caused to pass through' whereby the heating means both on itsway to the blower means and on its way from the blower means.

4. A structure'as recited in claim 3 where;

'in the heating means comprise a plurality of vertically extending-barsthrough which said pipes pass and which bars constitute supports forsaid pipes, the edges of said bars contacting with each other so thatcomplementally they to create within the heating means ducts constitutepartititions which constitute parts of the aforesaid ducts.

5. A forced circulation kiln of thechar .acter described comprising afloor, the

1s divided'into two out.-

space beneath which side ducts and a central duct, a pair of blowers tothe suction sides of which the outsideair ducts lead, the dischar esides of said blowers discharging into-t e said central duct and aheating unit comprising a plurality of horizontally disposed steam pipesextending entirely I across the kiln inwardly of the point of dischar eof the blowers and lying partly within al air is 'drawn through saidsteam pipes on its-way to the blowers and is forced through said steampipes on its way from the blowers.

6. In combination with a forced circulation kiln of the characterdescribed comprising a floor, the space beneath which is divided intooutside air conduits and a central air conduit, blower means, to the thesaid outside con--- charge side of which duits are connected and to thesuction side of which the central conduit -is connected, and a heatingmeans steampipes consisting of a units, each of said units consisting ofpliurality nd pipes, said heating means being disposed across all ofsaid conduit.- g

I 7AA structure as recited in "claim 6 in combination with combinedsupports and partitions through comprising a ba plurality of a the pipesof artitions constitute ls of thesaid contransversely substantially ofsaid -ducts so that the nk of.

of horizontally disposed return which the pipes of the unit pass andwhich partitions constitute an extension of Ports and the . and theversely extending heating unit of such length as to lie withinand'substantially span all of said ducts, and means for supplying aheating fluid 7 external source. a

1 0. A structure as recited in claim 9 to such unit from an wherein theheating unit comprises a bank of horizontal steam pipes and supports forsaid steam pipes which complement-ally constitute partitions, the spacesbetween which constitute parts of the said air ducts.

11. A structure as recited in claim 5 in combination with a plurality ofvertically disposed supports for the pipes through which said pipespass, the edges of said supports abutting each other, so thatcomplementally they constitute partitions, said partitions being alignedwith the corresponding wads of the several ducts to constituteextensions thereof. l

In testimony whereof vI aflix my signature.

MORITZ L. MUELLER.

